The Core Computational Facility will provide support for experimental efforts described in Projects 1-3. Ab initio methods and novel Monte Carlo and molecular dynamics schemes will be used to investigate the thermodynamics and kinetics of elementary reactions, electronic structures of products, reactants, and transition states, and particle growth pathways. The structures and reactive sites of metal oxide clusters will be determined using ab initio Monte Carlo and/or molecular dynamics methods. The Core Computational Facility will calculate reaction thermodynamics and kinetics of the reactions of metal oxide clusters with persistent free radicals. The Core Computational Facility will provide support for these studies by using ab initio methods to calculate activation energies and overall reaction thermodynamics (reaction energies, enthalpies, entropies, and free energies) in order to investigate various proposed reaction mechanisms. Spin densities of radical species will be calculated and used to correlate relative reactivities with toxicities. The Computational facilities will include local workstations, LSD's high performance computing facilities (www.hpc.lsu.edu), and the State of Louisiana's high performance computing network (www.loni.org). and LSU's state-of-the-art CCT concurrent computational facility (www.cct.lsu.edu). This Core will be led by Dr. Randall Hall and will include a senior post-doctoral associate who will direct the research efforts of existing students (both graduate and undergraduate). The group will use the ab initio programs Gaussian, Wien, and NWChem in parallel mode and hand written Monte Carlo and molecular dynamics programs. Calculations will use both density functional and correlated methods (such as MP2) and both all-electron and pseudopotential basis sets. The Monte Carlo methods will include Aggregation Volume Bias Monte Carlo, Configuration Bias Monte Carlo, and umbrella sampling and a recently developed path integral formalism that allows for the simultaneous treatment of electronic and geometric degrees of freedom. In addition, handwritten scripts in which molecular dynamics or Monte Carlo algorithms were combined with ab initio calculation of energies and forces to perform ab initio molecular dynamics or Monte Carlo simulations will be used.